Refactor hacky ID tables to struct rb_ast_id_table_t

The implementation of a local variable tables was represented as `ID*`,
but it was very hacky: the first element is not an ID but the size of
the table, and, the last element is (sometimes) a link to the next local
table only when the id tables are a linked list.

This change converts the hacky implementation to a normal struct.

1 files changed, 3 insertions, 3 deletions

diff --git a/ast.c b/ast.c
index 96116d43eb..8139fcd390 100644
--- a/ast.c
+++ b/ast.c
@@ -600,11 +600,11 @@ node_children(rb_ast_t *ast, const NODE *node)
         }
       case NODE_SCOPE:
         {
-            ID *tbl = node->nd_tbl;
-            int i, size = tbl ? (int)*tbl++ : 0;
+            rb_ast_id_table_t *tbl = node->nd_tbl;
+            int i, size = tbl ? tbl->size : 0;
             VALUE locals = rb_ary_new_capa(size);
             for (i = 0; i < size; i++) {
-                rb_ary_push(locals, var_name(tbl[i]));
+                rb_ary_push(locals, var_name(tbl->ids[i]));
             }
             return rb_ary_new_from_args(3, locals, NEW_CHILD(ast, node->nd_args), NEW_CHILD(ast, node->nd_body));
         }